1. Field of the Invention
This invention pertains to the field of release agents for molded rubber articles and particularly to the use of polysiloxane copolymers therefor.
2. Description of the Prior Art
In the manufacture of molded rubber articles, a release agent is required in order to be able to take the molded rubber goods from the molds and to prevent adhesion of the molded articles to the walls of the mold. Frequently, however, such a release agent is also required to reduce the friction between the molded rubber articles and the wall of a form-giving element.
Particularly difficult lubrication and release problems occur in the manufacture of so-called elbow hoses, such as those required in building automobiles and for washing machines and dry cleaning machines. In these procedures, a vulcanizable blank is pulled onto a plug which, at times, has a very complicated shape. After the vulcanization, the hot molded rubber article must be pulled from the plug. This is an operation which requires the use of considerable force. The force required is determined on the one hand by the shape of the plug and, on the other hand, by the adhesion of the molded article to the plug.
In order to avoid adhesion and to improve the ability to slide, such blanks, which are to be pulled onto a bent plug and vulcanized, have been treated with dispersions of silicone oils, glycerin and waxes. Admittedly, adhesion and friction are reduced by such means. However, it is desirable to further improve the sliding properties of such a lubricant and release agent. At the same time, it is particularly important that the lubricant and release agents can be removed without leaving a residue, so as not to impair the use of the elbow hoses. Preferably, it should be possible to remove the lubricants and release agents with cold water.